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Since plants on Earth evolved under broad-spectrum solar radiation, anytime they are grown exclusively under electric lighting that does not contain all wavelengths in similar proportion to those in sunlight, plant appearance and size could be uniquely different. Nevertheless, plants have been grown for decades under fluorescent (FL) (1) + incandescent (IN) (2) lamps as a sole source of lighting (SSL), and researchers have become comfortable that, in certain proportions of FL + IN for a given species, plants can appear "normal" relative to their growth outdoors. The problem with using such traditional SSLs for commercial production typically is short lamp lifespans and not obtaining enough photosynthetically active radiation (PAR, 400-700 nm) when desired. These limitations led to supplementation of FL + IN lamp outputs with longer-lived, high-intensity discharge (HID) lamps in growth chambers (3). As researchers became comfortable that mixes of orange-biased high-pressure sodium (HPS) and blue-biased metal halide (MH) HIDs together also could give normal plant growth at higher intensities, growth chambers and phytotrons subsequently were equipped mainly with HID lamps, with their intense thermal output filtered out by ventilated light caps or thermal-controlled water barriers. For the most part, IN and HID lamps have found a home in commercial protected horticulture, usually for night-break photoperiod lighting (IN) or for seasonal supplemental lighting (mostly HPS) in greenhouses. However, lack of economically viable options for SSL have held back aspects of year-round indoor agriculture from taking off commercially.

Publication Date:

May 31, 2015

Document ID:

20150009399

(Acquired Jun 03, 2015)

Subject Category:

LIFE SCIENCES (GENERAL)

Report/Patent Number:

KSC-E-DAA-TN23510

Document Type:

Book Chapter

Publisher Information:

R. Lopez and E. Runkle, Meister Media Worldwide

Contract/Grant/Task Num:

NNK11EA08C

Financial Sponsor:

NASA Kennedy Space Center; Cocoa Beach, FL United States

Organization Source:

NASA Kennedy Space Center; Cocoa Beach, FL United States

Description:

10p; In English

Distribution Limits:

Unclassified; Publicly available; Unlimited

Rights:

Copyright; Distribution under U.S. Government purpose rights; Under NASA contract NNK11EA08C